GCN Circular 24390

E.Moretti (IFAE, Barcelona), M. Axelsson (KTH and Stockholm Univ.),
D. Kocevski (NASA/MSFC) and N. Omodei (Stanford Univ.) report on behalf of
the Fermi-LAT Collaboration:

We have searched data collected by the Fermi Large Area Telescope (LAT) on
May 03, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in
spatial/temporal coincidence with the LIGO/Virgo trigger S190503bf (GCN
24377
Not found
 
 
).

We define "instantaneous coverage" as the integral over the region of the
LIGO probability map that is within the LAT field of view at a given a
time, and "cumulative coverage" as the integral of the instantaneous
coverage over time. Fermi-LAT had  instantaneous coverage of ~50% of the
LIGO probability at the time of the trigger (T0 = 2019-05-03 18:54:26 UTC),
and reached 100% cumulative coverage after ~7 ks.

We performed a search for a transient counterpart within the observed
region of the 90% contour of the LIGO map in a fixed time window from T0 to
T0 + 10 ks.

No significant new sources are found.

We also performed a search which adapted the time interval of the analysis
to the exposure of each region of the sky, and no additional excesses were
found.

Energy flux upper bounds for the fixed time interval between 100 MeV and
100 GeV for this search vary between 1.5e-10 and 9e-10 [erg/cm^2/s].

The Fermi-LAT point of contact for this event is Elena Moretti (
moretti@ifae.es).

The Fermi-LAT is a pair conversion telescope designed to cover the energy
band from 20 MeV to greater than 300 GeV It is the product of an
international collaboration between NASA and DOE in the U.S. and many
scientific institutions across France, Italy, Japan and Sweden.






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